2
LC MOS Single Supply,
a
12-Bit 600 kSPS ADC
AD7892
FEATURES FUNCTIONAL BLOCK DIAGRAM
Fast 12-Bit ADC with 1.47s Conversion Time
REF OUT/REF IN V
DD
600 kSPS Throughput Rate (AD7892-3)
500 kSPS Throughput Rate (AD7892-1, AD7892-2)
2k
+2.5V MODE
Single Supply Operation
AD7892
REFERENCE
On-Chip Track/Hold Amplifier
Selection of Input Ranges:
DB0
10 V or 5 V for AD7892-1
DB2
0 V to +2.5 V for AD7892-2 DB3/RFS
12-BIT
DB4/SCLK
2.5 V for AD7892-3
ADC
DB5/SDATA
V
High Speed Serial and Parallel Interface IN1 SIGNAL
DB10/LOW
SCALING
V
Low Power, 60 mW typ IN2
DB11/LOW
Overvoltage Protection on Analog Inputs (AD7892-1
TRACK/HOLD
and AD7892-3)
CLOCK
CONTROL LOGIC
CS RD EOC CONVST AGND DGND STANDBY
GENERAL DESCRIPTION The AD7892 is fabricated in Analog Devices Linear Compat-
2
The AD7892 is a high speed, low power, 12-bit A/D converter ible CMOS (LC MOS) process, a mixed technology process
that operates from a single +5 V supply. The part contains a that combines precision bipolar circuits with low power CMOS
1.47 s successive approximation ADC, an on-chip track/hold logic. It is available in a 24-lead, 0.3" wide, plastic or hermetic
amplifier, an internal +2.5 V reference and on-chip versatile DIP or in a 24-lead SOIC.
interface structures that allow both serial and parallel connec-
tion to a microprocessor. The part accepts an analog input range PRODUCT HIGHLIGHTS
of 10 V or 5 V (AD7892-1), 0 V to +2.5 V (AD7892-2) and 1. The AD7892-3 features a conversion time of 1.47 s and a
2.5 V (AD7892-3). Overvoltage protection on the analog inputs track/hold acquisition time of 200 ns. This allows a through-
for the AD7892-1 and AD7892-3 allows the input voltage to go put rate for the part up to 600 kSPS. The AD7892-1 and
to 17 V or 7 V respectively without damaging the ports. AD7892-2 operate with throughput rates of 500 kSPS.
The AD7892 offers a choice of two data output formats: a 2. The AD7892 operates from a single +5 V supply and con-
single, parallel, 12-bit word or serial data. Fast bus access times sumes 60 mW typ making it ideal for low power and portable
and standard control inputs ensure easy parallel interface to applications.
microprocessors and digital signal processors. A high speed
3. The part offers a high speed, flexible interface arrangement
serial interface allows direct connection to the serial ports of
with parallel and serial interfaces for easy connection to
microcontrollers and digital signal processors.
microprocessors, microcontrollers and digital signal
In addition to the traditional dc accuracy specifications such as processors.
linearity, full-scale and offset errors, the part is also specified for
dynamic performance parameters including harmonic distortion
and signal-to-noise ratio.
REV. C
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
use, nor for any infringements of patents or other rights of third parties
Tel: 781/329-4700 World Wide Web Site: (V = +5 V 5%, AGND = DGND = 0 V, REF IN = +2.5 V. All specifications T to T
DD MIN MAX
AD7892SPECIFICATIONS unless otherwise noted.)
1 2
Parameter A Versions B Versions S Version Unit Test Conditions/Comments
DYNAMIC PERFORMANCE
AD7892-1, AD7892-2 f = 100 kHz. f = 500 kSPS
IN SAMPLE
3
Signal to (Noise + Distortion) Ratio 70 70 70 dB min
3
Total Harmonic Distortion 78 78 78 dB max typ 84 dB
3
Peak Harmonic or Spurious Noise 79 79 79 dB max
3
Intermodulation Distortion fa = 49 kHz, fb = 50 kHz
2nd Order Terms 78 78 78 dB max typ 84 dB
3rd Order Terms 78 78 78 dB max typ 84 dB
AD7892-3 f = 100 kHz. f = 600 kSPS
IN SAMPLE
3
Signal to (Noise + Distortion) Ratio 70 70 dB min
3
Total Harmonic Distortion 78 78 dB max
3
Peak Harmonic or Spurious Noise 79 79 dB max
3
Intermodulation Distortion fa = 49 kHz, fb = 50 kHz
2nd Order Terms 78 78 dB max
3rd Order Terms 78 78 dB max
DC ACCURACY
Resolution 12 12 12 Bits
Minimum Resolution for Which No
Missing Codes Are Guaranteed 12 12 12 Bits
3
Relative Accuracy 1.5 1 1 LSB max
3
Differential Nonlinearity 1 1 1 LSB max
AD7892-1
3
Positive Full-Scale Error 4 4 5 LSB max
3
Negative Full-Scale Error 4 4 5 LSB max
3
Bipolar Zero Error 3 2 3 LSB max
AD7892-3
3
Positive Full-Scale Error 4 4 LSB max
3
Negative Full-Scale Error 4 4 LSB max
3
Bipolar Zero Error 4 3 LSB max
AD7892-2
3
Positive Full-Scale Error 5 5 5 LSB max
3
Unipolar Offset Error 4 3 4 LSB max
ANALOG INPUT
AD7892-1
Input Voltage Range 10 10 10 Volts Input Applied to V with V Grounded
IN1 IN2
Input Voltage Range 5 5 5 Volts Input Applied to V and V
IN1 IN2
Input Resistance 8 8 8 k min Input Applied to V with V Grounded
IN1 IN2
AD7892-2
Input Voltage Range on V 0 to +2.5 0 to +2.5 0 to +2.5 Volts Input Applied to V
IN1 IN1
Input Current 10 10 50 nA max
Input Voltage Range on V 50 50 50 mV max
IN2
AD7892-3
Input Voltage Range on V 2.5 2.5 Volts Input Applied to V
IN1 IN1
Input Resistance 2 2 k min
REFERENCE OUTPUT/INPUT
REF IN Input Voltage Range 2.375/2.625 2.375/2.625 2.375/2.625 V min/V max 2.5 V 5%
Input Impedance 1.6 1.6 1.6 k min Resistor Connected to Internal Reference Node
4
Input Capacitance 10 10 10 pF max
REF OUT Output Voltage 2.5 2.5 2.5 V nom
REF OUT Error @ +25C 10 10 10 mV max
T to T 20 20 25 mV max
MIN MAX
REF OUT Temperature Coefficient 25 25 25 ppm/C typ
REF OUT Output Impedance 5.5 5.5 5.5 k nom
LOGIC INPUTS
Input High Voltage, V 2.4 2.4 2.4 V min V = 5 V 5%
INH DD
Input Low Voltage, V 0.8 0.8 0.8 V max V = 5 V 5%
INL DD
Input Current, I 10 10 10 A max V = 0 V to V
IN IN DD
4
Input Capacitance, C 10 10 10 pF max
IN
2 REV. C